Signal is a fully featured messaging app, built with a privacy-first mindset.
Thomas Trutschel/Getty Images
  • Signal is a free messaging app that uses end-to-end encryption to keep your messages private.
  • When you send a message, the only people who can see that message are the recipients — not even the company that runs Signal can see what you send.
  • You can use Signal to send texts, photos, videos, and voice messages, as well as manage group chats.
  • Visit Business Insider's Tech Reference library for more stories .


Just this year, Signal has become one of the most popular messaging apps around. Favoured by tech giants, cybersecurity experts, journalists, government officials, and many more, Signal has gone from a darling secret of the security community to something even the non-tech savvy are using.

Signal is known for its incredible security and wealth of features. On an internet where it seems that more and more businesses are trying to track you, Signal can keep all of your conversations private.

Here's how Signal works, and why it's so popular.

How Signal works

Signal is safer and more secure than most messengers because of a process called "end-to-end encryption." This works by encoding a sender's message in such a way that only the intended receiver's device can unlock it. 

Neither Signal, nor your phone company, nor the government can read your messages. That's why it's remained popular with journalists, government officials, and anyone else who deals with classified materials. Over the summer, droves of protesters concerned with law enforcement intercepting their communications downloaded the app as well.

Signal lets you chat securely.
Signal

However, Signal's messages are only secure if both the sender and receiver are on the app. Otherwise, you're just sending standard text messages back and forth.

If you prefer to communicate through Signal, the app has a simple feature to invite someone to download it. Blocking someone from contacting you through the app is just as easy.

But encryption itself isn't a unique feature. Apps like iMessage, Telegraph and WeChat all do it to an extent. However, Signal's source code is publicly available, so experts have been able to poke and prod at its defenses for years, strengthening it in the process.

Signal's key features

Signal is similar to other messaging apps, but with a lot more security features. It's available for free on iPhone, Android, Mac, and PC.

Android users can even set their default messaging app to Signal if they want to.

There's a Signal app on nearly every major system.
Signal.org

On a basic level, you can have one-on-one conversations with someone or start a group chat. In these chats, you can send pictures, videos, internet links, voice messages, and more. You can even send and react to messages with emojis, much like on Slack and Discord.

Signal's beta version is testing new kinds of chats with forum-like features. Those include group admins, updates, timers for disappearing messages. For now, groups are capped at 150 people, but adding and removing new people from a group is simple.

If you're concerned about someone accessing the Signal app from your phone, you can lock the app with the same passcode or fingerprint scan normally used to lock your phone.

Signal requires a phone number to join the app. To keep yours private, you can sign up with a Google voice number.  Apple users will want to visit their privacy settings within the app and turn off "Show Calls in Recents" to prevent your history from syncing with the cloud.

You can also set your messages to disappear over time, or photos to disappear after a single viewing.

In short, Signal is focused on privacy first, and gives you a host of tools to manage that privacy.

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